AA6061 sheet was prepared by cold rolling and low-temperature aging. The tensile mechanical properties of the sheet at room temperature and cryogenic temperature (-100 ℃) were tested. The microstructure of the plates was analyzed by scanning electron microscope(SEM), X-ray diffraction (XRD) and transmission electron microscope(TEM). The results show that the maximum difference of the ultimate tensile strength between cryogenic temperature and room temperature is 37.7 MPa for the sheet with a rolling reduction rate of 50% and aging at 120 ℃ for 30 h, and the minimum difference is 2.1 MPa aging at 140 ℃ for 30 h. With the increase of aging time, the cryogenic performance first increases and then decreases. The overall performance of samples aged at 140 ℃ is lower than that aged at 120 ℃ because of the over aging of material. With the increase of rolling reduction rate, aging time and temperature, the lattice friction stress, dislocation strengthening and precipitation strengthening of the material gradually approach the ultimate value, and the strength difference of tensile samples at room temperature and cryogenic temperature decreases gradually.